Deep learning in ophthalmology: The technical and clinical considerations

The advent of computer graphic processing units, improvement in mathematical models and availability of big data has allowed artificial intelligence (AI) using machine learning (ML) and deep learning (DL) techniques to achieve robust performance for broad applications in social-media, the internet of things, the automotive industry and healthcare. DL systems in particular provide improved capability in image, speech and motion recognition as well as in natural language processing. In medicine, significant progress of AI and DL systems has been demonstrated in image-centric specialties such as radiology, dermatology, pathology and ophthalmology. New studies, including pre-registered prospective clinical trials, have shown DL systems are accurate and effective in detecting diabetic retinopathy (DR), glaucoma, age-related macular degeneration (AMD), retinopathy of prematurity, refractive error and in identifying cardiovascular risk factors and diseases, from digital fundus photographs. There is also increasing attention on the use of AI and DL systems in identifying disease features, progression and treatment response for retinal diseases such as neovascular AMD and diabetic macular edema using optical coherence tomography (OCT). Additionally, the application of ML to visual fields may be useful in detecting glaucoma progression. There are limited studies that incorporate clinical data including electronic health records, in AL and DL algorithms, and no prospective studies to demonstrate that AI and DL algorithms can predict the development of clinical eye disease. This article describes global eye disease burden, unmet needs and common conditions of public health importance for which AI and DL systems may be applicable. Technical and clinical aspects to build a DL system to address those needs, and the potential challenges for clinical adoption are discussed. AI, ML and DL will likely play a crucial role in clinical ophthalmology practice, with implications for screening, diagnosis and follow up of the major causes of vision impairment in the setting of ageing populations globally

Optical Coherence Tomography in the UK Biobank Study – Rapid Automated Analysis of Retinal Thickness for Large Population-Based Studies

Purpose: To describe an approach to the use of optical coherence tomography (OCT) imaging in large, population-based studies, including methods for OCT image acquisition, storage, and the remote, rapid, automated analysis of retinal thickness. Methods: In UK Biobank, OCT images were acquired between 2009 and 2010 using a commercially available “spectral domain” OCT device (3D OCT-1000, Topcon). Images were obtained using a raster scan protocol, 6 mm x 6 mm in area, and consisting of 128 B-scans. OCT image sets were stored on UK Biobank servers in a central repository, adjacent to high performance computers. Rapid, automated analysis of retinal thickness was performed using custom image segmentation software developed by the Topcon Advanced Biomedical Imaging Laboratory (TABIL). This software employs dual-scale gradient information to allow for automated segmentation of nine intraretinal boundaries in a rapid fashion. Results: 67,321 participants (134,642 eyes) in UK Biobank underwent OCT imaging of both eyes as part of the ocular module. 134,611 images were successfully processed with 31 images failing segmentation analysis due to corrupted OCT files or withdrawal of subject consent for UKBB study participation. Average time taken to call up an image from the database and complete segmentation analysis was approximately 120 seconds per data set per login, and analysis of the entire dataset was completed in approximately 28 days. Conclusions: We report an approach to the rapid, automated measurement of retinal thickness from nearly 140,000 OCT image sets from the UK Biobank. In the near future, these measurements will be publically available for utilization by researchers around the world, and thus for correlation with the wealth of other data collected in UK Biobank. The automated analysis approaches we describe may be of utility for future large population-based epidemiological studies, clinical trials, and screening programs that employ OCT imaging

Superoxide dismutase A antigens derived from molecular analysis of sarcoidosis granulomas elicit systemic Th-1 immune responses

<p>Abstract</p> <p>Background</p> <p>Sarcoidosis is an idiopathic granulomatous disease with pathologic and immunologic features similar to tuberculosis. Routine histologic staining and culture fail to identify infectious agents. An alternative means for investigating a role of infectious agents in human pathogenesis involves molecular analysis of pathologic tissues for microbial nucleic acids, as well as recognition of microbial antigens by the host immune system. Molecular analysis for superoxide dismutase A (sodA) allows speciation of mycobacteria. SodA is an abundantly secreted virulence factor that generates cellular immune responses in infected hosts. The purpose of this study is to investigate if target antigens of the sarcoidosis immune response can be identified by molecular analysis of sarcoidosis granulomas.</p> <p>Methods</p> <p>We detected sodA amplicons in 12 of 17 sarcoidosis specimens, compared to 2 of 16 controls (p = 0.001, two-tailed Fisher's exact test), and 3 of 3 tuberculosis specimens (p = 0.54). Analysis of the amplicons revealed sequences identical to <it>M. tuberculosis </it>(MTB) complex, as well as sequences which were genetically divergent. Using peripheral blood mononuclear cells (PBMC) from 12 of the 17 sarcoidosis subjects, we performed enzyme-linked immunospot assay (ELISPOT) to assess for immune recognition of MTB sodA peptides, along with PBMC from 26 PPD- healthy volunteers, and 11 latent tuberculosis subjects.</p> <p>Results</p> <p>Six of 12 sarcoidosis subjects recognized the sodA peptides, compared to one of 26 PPD- controls (p = 0.002), and 6/11 PPD+ subjects (p = .68). Overall, 10 of the 12 sarcoidosis subjects from whom we obtained PBMC and archival tissue possessed molecular or immunologic evidence for sodA.</p> <p>Conclusion</p> <p>Dual molecular and immunologic analysis increases the ability to find infectious antigens. The detection of Th-1 immune responses to sodA peptides derived from molecular analysis of sarcoidosis granulomas reveals that these are among the target antigens contributing to sarcoidosis granulomatous inflammation.</p

A comparison of an interferon-gamma release assay and tuberculin skin test in refractory inflammatory disease patients screened for latent tuberculosis prior to the initiation of a first tumor necrosis factor α inhibitor

Treatment with TNFα inhibitors increases risk of reactivating a latent tuberculosis\infection (LTBI). Therefore screening, prior to therapy with TNFα inhibitors, has been recommended, even in low-endemic areas such as well-developed Western Europe countries. We evaluated interferon-gamma release assay (IGRA), as opposed to tuberculin skin test (TST), for detection of LTBI in refractory inflammatory disease patients prior to the initiation of a first TNFα inhibitor. In addition, we evaluated the impact of impaired cellular immunity on IGRA. Patients starting on TNFα inhibition were screened for LTBI by TST and IGRA (Quantiferon-TB Gold). Data on tuberculosis exposure and Bacillus Calmette–Guérin (BCG) vaccination were obtained. Cellular immunity was assessed by CD4+ T lymphocyte cell count. Nine out of 56 patients (16.1%) tested positive for LTBI. A concordant positive result was present in three patients with a medical history of tuberculosis exposure. Six patients with discordant test results had either: (1) a negative TST and positive IGRA in combination with a medical history of tuberculosis exposure (n = 1) or (2) a positive TST and negative IGRA in combination with BCG vaccination (n = 3) or a medical history of tuberculosis exposure (n = 2). CD4+ T lymphocyte cell counts were within normal limits, and no indeterminate results of IGRA were present. IGRA appears reliable for confirming TST and excluding a false positive TST (due to prior BCG vaccination) in this Dutch serie of patients. In addition, IGRA may detect one additional case of LTBI out of 56 patients that would otherwise be missed using solely TST. Immune suppression appears not to result significantly in lower CD4+ T lymphocyte cell counts and indeterminate results of IGRA, despite systemic corticosteroid treatment in half of the patients. Confirmation in larger studies, including assessment of cost-effectiveness, is required

Experimental Assessment of the Role of Acetaldehyde in Alcoholic Cardiomyopathy

Alcoholism is one of the major causes of non-ischemic heart damage. The myopathic state of the heart due to alcohol consumption, namely alcoholic cardiomyopathy, is manifested by cardiac hypertrophy, compromised ventricular contractility and cardiac output. Several mechanisms have been postulated for alcoholic cardiomyopathy including oxidative damage, accumulation of triglycerides, altered fatty acid extraction, decreased myofilament Ca(2+ )sensitivity, and impaired protein synthesis. Despite intensive efforts to unveil the mechanism and ultimate toxin responsible for alcohol-induced cardiac toxicity, neither has been clarified thus far. Primary candidates for the specific toxins are ethanol, its first and major metabolic product - acetaldehyde (ACA) and fatty acid ethyl esters. Evidence from our lab suggests that ACA directly impairs cardiac function and promotes lipid peroxidation resulting in oxidative damage. The ACA-induced cardiac contractile depression may be reconciled with inhibitors of Cytochrome P-450 oxidase, xanthine oxidase and lipid peroxidation Unfortunately, the common methods to investigate the toxicity of ACA have been hampered by the fact that direct intake of ACA is toxic and unsuitable for chronic study, which is unable to provide direct evidence of direct cardiac toxicity for ACA. In order to overcome this obstacle associated with the chemical properties of ACA, our laboratory has used the chronic ethanol feeding model in transgenic mice with cardiac over-expression of alcohol dehydrogenase (ADH) and an in vitro ventricular myocyte culture model. The combination of both in vivo and in vitro approaches allows us to evaluate the role of ACA in ethanol-induced cardiac toxicity and certain cellular signaling pathways leading to alcoholic cardiomyopathy

Evidence of CD4+ T cell-mediated immune pressure on the Hepatitis C virus genome

Hepatitis C virus (HCV)-specific T cell responses are critical for immune control of infection. Viral adaptation to these responses, via mutations within regions of the virus targeted by CD8+ T cells, is associated with viral persistence. However, identifying viral adaptation to HCV-specific CD4+ T cell responses has been difficult although key to understanding anti-HCV immunity. In this context, HCV sequence and host genotype from a single source HCV genotype 1B cohort (n = 63) were analyzed to identify viral changes associated with specific human leucocyte antigen (HLA) class II alleles, as these variable host molecules determine the set of viral peptides presented to CD4+ T cells. Eight sites across the HCV genome were associated with HLA class II alleles implicated in infection outcome in this cohort (p ≤ 0.01; Fisher’s exact test). We extended this analysis to chronic HCV infection (n = 351) for the common genotypes 1A and 3A. Variation at 38 sites across the HCV genome were associated with specific HLA class II alleles with no overlap between genotypes, suggestive of genotype-specific T cell targets, which has important implications for vaccine design. Here we show evidence of HCV adaptation to HLA class II-restricted CD4+ T cell pressure across the HCV genome in chronic HCV infection without a priori knowledge of CD4+ T cell epitopes

The Evolution of Compact Binary Star Systems

We review the formation and evolution of compact binary stars consisting of white dwarfs (WDs), neutron stars (NSs), and black holes (BHs). Binary NSs and BHs are thought to be the primary astrophysical sources of gravitational waves (GWs) within the frequency band of ground-based detectors, while compact binaries of WDs are important sources of GWs at lower frequencies to be covered by space interferometers (LISA). Major uncertainties in the current understanding of properties of NSs and BHs most relevant to the GW studies are discussed, including the treatment of the natal kicks which compact stellar remnants acquire during the core collapse of massive stars and the common envelope phase of binary evolution. We discuss the coalescence rates of binary NSs and BHs and prospects for their detections, the formation and evolution of binary WDs and their observational manifestations. Special attention is given to AM CVn-stars -- compact binaries in which the Roche lobe is filled by another WD or a low-mass partially degenerate helium-star, as these stars are thought to be the best LISA verification binary GW sources.Comment: 105 pages, 18 figure

A CLINICAL STUDY OF INHALANT ANAESTHESIA IN DOGS

A clinical trial was undertaken using three different inhalant anaesthetic agents and one intravenous anaesthetic agent in dogs undergoing routine desexing surgery. Healthy adult dogs undergoing either ovariohysterectomy or castration were assessed as to their demeanour, with the more excitable dogs being placed in groups receiving premedication with acepromazine and morphine. All dogs were then randomly assigned an anaesthetic agent for induction of general anaesthesia. The agents were the inhalants halothane, isoflurane and sevoflurane, and the intravenous agent propofol. Inhalant inductions were undertaken using a tight fitting mask attached to a standard anaesthetic machine with a rebreathing circuit, with the maximum dose of inhalant available from a standard vaporiser. Propofol inductions were undertaken via intravenous catheter. Dogs induced with propofol were randomly assigned one of the three inhalant agents for maintenance. Those induced by inhalant agent were maintained using the same agent. The surgical procedure was undertaken in standard fashion, as was recovery from anaesthesia. All dogs received the non-steroidal anti-inflammatory agent meloxicam. Data collection was divided into three stages: induction, maintenance, and recovery from anaesthesia. Variables measured at induction of anaesthesia were time to intubation, number of intubation attempts, tolerance of mask, quality of induction and quality of transfer to the maintenance stage. Standard variables for monitoring of anaesthesia were recorded throughout the maintenance of anaesthesia. Variables measured at recovery were time to righting, time to standing and quality of recovery. The mean time to intubation when using the newer inhalant sevoflurane (196.2 ± 14.8sec, mean ± SE) was not significantly different to that for halothane (221.4 ± 14.0sec) or isoflurane (172.4 ± 15.0sec). Time to intubation with isoflurane was significantly faster than with halothane. Mean time to intubation with propofol (85.4 ± 7.7sec) was significantly faster than that for any of the three inhalants. Choice of inhalant had no effect on quality of induction. The use of premedication significantly improved the quality of induction. The use of propofol for induction likewise significantly improved the quality of induction. Standard cardiorespiratory variables measured during the maintenance phase of anaesthesia remained within normal clinical ranges for all three inhalants, and were therefore not further analysed. Choice of inhalant agent had no significant effect on the time to righting or standing in recovery. The use of propofol for induction had no effect on these variables. Animals placed in groups receiving premedication had significantly longer times to righting and standing. The oesophageal temperature at the end of the procedure had a significant effect on times to righting and standing, with lower temperatures contributing to slower recoveries. Independent of procedure time, male dogs had shorter times to righting than female dogs

An exploratory qualitative assessment of factors influencing childhood vaccine providers' intention to recommend immunization in the Netherlands

<p>Abstract</p> <p>Background</p> <p>Under the Dutch national immunization program (NIP), childhood vaccination is not mandatory, but its recommendation by childhood vaccine providers (CVP) is important for maintaining high vaccination coverage. We therefore examined factors related to providers' intentions to recommend vaccinations to parents of young children.</p> <p>Methods</p> <p>We conducted four focus group discussions with nurses and physicians who provide vaccines to children 0-4 years old in diverse regions of the Netherlands. Three groups represented CVPs at child welfare centers (CWCs) serving the general population, with the fourth representing anthroposophical CWCs. Elements of the Theory of Planned Behaviour (TPB) were used to design the groups; thematic analysis was used to structure and analyze the dataset.</p> <p>Results</p> <p>Four main themes emerged, including 1) perceived responsibility: to promote vaccines and discuss pros and cons with parents (although this was usually not done if parents readily accepted the vaccination); 2) attitudes toward the NIP: mainly positive, but doubts as to NIP plans to vaccinate against diseases with a low perceived burden; 3) organizational factors: limited time and information can hamper discussions with parents; 4) relationship with parents: crucial and based mainly on communication to establish trust. Compared to CVPs at standard CWCs, the anthroposophical CWCs spent more time communicating and were more willing to adapt the NIP to individual cases.</p> <p>Conclusions</p> <p>Our qualitative assessment provides an overview of beliefs associated with providers' intention to recommend vaccinations. They were motivated to support the NIP, but their intentions to recommend vaccinations were affected by the perceived relevance of the vaccines, practical issues like limited time and by certain types of resistant parents. These results will inform future studies to test the magnitude and relative impact of these factors.</p

Analysis of the FGF gene family provides insights into aquatic adaptation in cetaceans

Cetacean body structure and physiology exhibit dramatic adaptations to their aquatic environment. Fibroblast growth factors (FGFs) are a family of essential factors that regulate animal development and physiology; however, their role in cetacean evolution is not clearly understood. Here, we sequenced the fin whale genome and analysed FGFs from 8 cetaceans. FGF22, a hair follicle-enriched gene, exhibited pseudogenization, indicating that the function of this gene is no longer necessary in cetaceans that have lost most of their body hair. An evolutionary analysis revealed signatures of positive selection for FGF3 and FGF11, genes related to ear and tooth development and hypoxia, respectively. We found a D203G substitution in cetacean FGF9, which was predicted to affect FGF9 homodimerization, suggesting that this gene plays a role in the acquisition of rigid flippers for efficient manoeuvring. Cetaceans utilize low bone density as a buoyancy control mechanism, but the underlying genes are not known. We found that the expression of FGF23, a gene associated with reduced bone density, is greatly increased in the cetacean liver under hypoxic conditions, thus implicating FGF23 in low bone density in cetaceans. Altogether, our results provide novel insights into the roles of FGFs in cetacean adaptation to the aquatic environment.ope